169 results about "Multiferroics" patented technology

A magnetostrictive-piezoelectric multiferroic single- or multi-domain nanomagnet whose magnetization can be rotated through application of an electric field across the piezoelectric layer has a structure that can include either a shape-anisotropic mangnetostrictive nanomagnet with no magnetocrystalline anisotropy or a circular nanomagnet with biaxial magnetocrystalline anisotropy with dimensions of nominal diameter and thickness. This structure can be used to write and store binary bits encoded in the magnetization orientation, thereby functioning as a memory element, or perform both Boolean and non-Boolean computation, or be integrated with existing magnetic tunneling junction (MTJ) technology to perform a read operation by adding a barrier layer for the MTJ having a high coercivity to serve as the hard magnetic layer of the MTJ, and electrical contact layers of a soft material with small Young's modulus. Equivalently, mangnetostrictive nanomagnetic elements whose magnetization is rotated by strain transferred from the substrate that has acoustic waves propagating on the substrate can be used.

The invention relates to a magnetic recording medium based on a multiferroic film, comprising a substrate and a medium layer growing on the substrate. The medium is characterized in that the medium layer comprises a ferroelectric structure unit formed by a ferroelectric material and a ferromagnetic structure unit formed by a ferromagnetic material. The write-in method comprises the following steps: an electric signal generated by a signal source is applied to two ends of the ferroelectric structure unit; an impulse voltage signal generated by the signal source changes the polarized state of a ferroelectric layer; through a magnetoelectric coupling effect, changes of the polarized state can further change the magnetization direction in the ferroelectric structure unit so as to record the state of an electric signal and complete information storage. Compared with the prior art, the invention provides the novel magnetic recording medium of the multiferroic composite material and several structures for recording the medium based on the traditional magnetic recording medium; and the medium using the multiferroic materials for recording can realize the magnetic recording method for electric write-in, and has wide application prospect for novel multifunctional devices with high density storage.

The invention discloses laminated ferroelectric/magnetic multiferroic and magnetoelectric composite film and preparation method thereof. The film comprises a substrate, a ferroelectric oxide layer and a magnetic oxide layer, and also a buffer layer positioned between the substrate layer and the ferroelectric oxide layer or the magnetic oxide layer. The layer can be LaNiO3, YBa2Cu3O7-x or SrRuO3, among which LaNiO3 is preferred. The preparation method comprises the following steps: firstly, buffer layer sol is prepared; secondly, the buffer layer sol is uniformly coated on the substrate to obtain the buffer layer; thirdly, sol of the ferroelectric oxide layer and the magnetic oxide layer is respectively prepared; fourthly, the sol obtained in step 3 is coated on the buffer layer, and then the end product is obtained. After the composite film is introduced into the buffer layer, the stress restraint of the substrate to the composite film is effectively reduced, the magnetoelectric coupling performance of the composite film with laminated structure is obviously enhanced, the cost is reduced, the preparation technique is simple, the requirement on the equipment is low, and the compatibility with the prior technique is good.

The invention discloses a preparation method of a self-supporting multiferroics composite film. According to the method, a plating platinum silicon chip comprising a silicon chip layer, an interface layer and a nano-scale thickness platinum thin layer is adopted, the plating platinum silicon chip is put into a hydrofluoric acid solution to make the interface layer of the plating platinum silicon chip react with the hydrofluoric acid to be etched, the platinum film disengages from the silicon chip and floats on the solution surface, the platinum film is transferred into a vessel filled with deionized water for washing, the platinum film is flatly paved on a substrate prepared by an exotic material and is dried and a ferroelectric layer film and a ferromagnetic layer film are deposited in order on the platinum film. Compared to the prior art, the preparation method of the invention is characterized by low cost, mild preparation condition and simple and controllable technology. Besides, the self-supporting multiferroics composite film obtained is more sensitive to extraneous stimulations because the film is free from the influence of a substrate fettering force and the magnetic electric coupling coefficient of the multiferroics composite film can be raised.

The present invention is to provide a semiconductor memory device capable of providing excellent storage properties, scaling and high integration and a method of fabricating the same. A semiconductor memory device has a multiferroic film exhibiting ferroelectricity and ferromagnetism, a channel region on an interface of a semiconductor substrate below the multiferroic film, source and drain regions formed on both sides of the channel region, a gate electrode (data write electrode) applying gate voltage to the multiferroic film to write data in such a way that the orientation of magnetization is changed as corresponding to the orientation of dielectric polarization, and source and drain electrodes (data read electrodes) that read data based on a deviation in a flow of the carrier, the deviation caused by applying the Lorentz force to the carrier flowing in the channel region from a magnetic field occurring in the channel region because of magnetization.

The invention relates to a multiferroic ferrotitanium bismuth cobaltates ceramic material with laminated structure and a preparation method thereof, which pertains to the technical field of oxide ceramic material preparation. Bi4Ti3O12 and BiCoO3 are implanted in BiFeO3 to generate Bi5Fe0.5Co0.5Ti3O15 (BFCT). The technology is simple and reasonable, and has good compatibility with current solid phase technology; the sample preparation temperature is far lower than that of current technology, thus greatly reducing energy consumption and facilitating industrialized production. In the BFCT, due to relative orderly arrangement of Fe-O and Co-O octahedron, local coupling of Fe-O-Co can be obtained, thus leading the magnetism of sample to be high.

The invention discloses a logic device based on spin wave interference and a multiferroic material. The logic device comprises five functional zones, namely, a spin wave excitation zone, a spin wave frequency division zone, an electric field regulation and control zone, a spin wave interference zone, and a spin wave detection zone; the basic structure and shape of the logic device are achieved through a spin wave transmission medium; due to the dispersion relation of spin waves in the medium, the spin wave transmission direction and model change in case of an external magnetic field or an internal magnetism change of the medium. The logic device provided by the invention can be used for achieving information transmission and logic operation; the spin waves are based on electron spin, and a regulation and control voltage is based on an electric field, so that electron generation or hole movements are eliminated, and the joule heat produced by electric current and the problem of quiescent dissipation due to leak current are effectively avoided.

Multiferroic articles including highly resistive, strongly ferromagnetic strained thin films of BiFe_0.5Mn_0.5O₃ (“BFMO”) on (001) strontium titanate and Nb-doped strontium titanate substrates were prepared. The films were tetragonal with high epitaxial quality and phase purity. The magnetic moment and coercivity values at room temperature were 90 emu/cc (H=3 kOe) and 274 Oe, respectively. The magnetic transition temperature was strongly enhanced up to approximately 600 K, which is approximately 500 K higher than for pure bulk BiMnO₃.

The invention discloses a multiferroic Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3-NiFe2O4 composite film and a preparation method thereof. The composite film comprises a Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 crystalline state film and a NiFe2O4 crystalline state film which are compounded together. The preparation method comprises the following steps: respectively preparing a Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 precursor solution and a NiFe2O4 precursor solution; and spinning on a substrate to prepare a multilayer NiFe2O4 film, and spinning on the NiFe2O4 film to prepare a multilayer Bi0.96-xSr0.04RExFe0.94Mn0.04Cr0.02O3 film, thereby obtaining the target product. The equipment requirement is simple, the prepared film is high in uniformity, the doping amount is easy to control, and the ferroelectric properties and ferromagnetic properties of the film are greatly improved. Meanwhile, the leakage current density of the film is effectively reduced.

The invention provides a novel class of room-temperature, single-phase, magnetoelectric multiferroic (PbFe_0.67W_0.33O₃)_x (PbZr_0.53Ti_0.47O₃)_1-x (0.2≦x≦0.8) (PFW_x−PZT_1-x) thin films that exhibit high dielectric constants, high polarization, weak saturation magnetization, broad dielectric temperature peak, high-frequency dispersion, low dielectric loss and low leakage current. These properties render them to be suitable candidates for room-temperature multiferroic devices. Methods of preparation are also provided.

A memory cell includes a magnetoresistive sensor that comprises layers that include a free layer. The magnetoresistive sensor conducts a read current representative of data stored in the memory cell during a read interval. A first write conductor carries a write current that writes data in the free layer. At least one of the layers comprises a multiferroic layer formed of multiferroic material.

The invention relates to a polymer-based multiferroic magnetoelectric composite material having both ferroelectric properties and ferromagnetic properties. The composite material is characterized by being formed through mixing up one-dimensional OD-MFe2O4 ferromagnetic elements with the fluoropolymer cPVDF material. The one-dimensional OD-MFe2O4 ferromagnetic elements are obtained through growing an MFe2O4 ferromagnetic compound on the surface of a one-dimensional functionalized material, wherein M=Fe, Co, Ni, Mn and Zn. According to the technical scheme of the invention, ferrites (MFe2O4, M=Fe, Co, Ni, Mn and Zn) and magnetic nanoparticles are loaded on the surface of the one-dimensional functionalized material through the in-situ assembling process, so that the one-dimensional material-magnetic nano-material (OD-MFe2O4) of a specific dimension and a specific surface activity is automatically synthesized. Therefore, the uniform dispersion of ferromagnetic OD-MFe2O4 in a ferroelectric polymer matrix is realized through compounding the ferroelectric polymer matrix with ferromagnetic OD-MFe2O4. Meanwhile, the good integration of an inorganic phase and an organic phase is realized. As a result, a ferromagnetic phase is highly ordered in a composite system. The wholly new multiferroic magnetoelectric composite material having both ferroelectric properties and ferromagnetic properties is prepared.

The invention provides a single-phase oxide multiferroic ceramic with exchange bias effect. The single-phase oxide multiferroic ceramic is as shown in the formula (I): Bi10Fe5.9Co0.1Ti3O30 (I). The single-phase oxide multiferroic ceramic has high Curie temperature, has ferroelectricity and ferromagnetism under the room temperature at the same time, and has intrinsic exchange bias effect. Not only a magnetic field can be regulated and controlled, but also an electric field can be regulated and controlled, the possibility of encoding storage information through the adoption of electric polarization and magnetic polarization at the same is provided, and then a magneto-electric mutual-control nonvolatile storage magnetic medium with ultrahigh storage density becomes possible.

The invention relates to a lead-free nontoxic low-frequency multiferroic nanoparticle magnetic-electric composite material and a preparation method thereof. The low-frequency multiferroic nanoparticle magnetic-electric composite material has magnetic-electric coupling effect. The low-frequency multiferroic nanoparticle magnetic-electric composite material has a chemical formula of xCoFe2O4-(1-x)[0.948(K0.5Na0.5)NbO3-0.052LiSbO3], wherein the optimal mol doping quantity x is 0.2-0.4mol. The parent phase of the composite particle material is 0.948(K0.5Na0.5)NbO3-0.052LiSbO3 with ferroelectricity, which is prepared by using a traditional solid phase method, and the doping phase thereof is a nanoparticle CoFe2O4 with ferroelectricity, which is prepared by using a sol-gel method. The multiferroic particle magnetic-electric composite material has the characteristics of better magnetic-electric coupling property, higher hardness, durability, and the like compared with the similar lead-free particle composite materials; and the preparation method is simple, low in the requirement on production equipment, and easy to massive production. The multiferroic particle magnetic-electric composite material has better ferroelectricity and stronger ferromagnetism and magnetic-electric coupling property, obtains wide application prospect in the fields of a sensor, a capacitor, a magnetic-electric storage, and the like, and achieves important function on the aspect of basic physics research.

A polycrystalline ferroelectric and/or multiferroic oxide article includes a substrate having a biaxially textured surface; at least one biaxially textured buffer layer supported by the substrate; and a biaxially textured ferroelectric or multiferroic oxide layer supported by the buffer layer. Methods for making polycrystalline ferroelectric and/or multiferroic oxide articles are also disclosed.

The present invention relates to a preparation method of a complex phase multiferroic material. The method of the present invention comprises the steps of applying an electric field on a substrate toenable a ferroelectric substrate to generate the stress pre-deformation, or applying the tensile stress or pressure stress on the ferroelectric substrate via a mechanical device to generate the pre-deformation; growing a ferromagnetic film on a pre-deformed ferroelectric film substrate via the methods, such as the pulsed laser deposition, the magnetron sputtering, the molecular beam epitaxy, etc.;after the ferromagnetic film is prepared, removing the electric field or the mechanical device on the ferroelectric substrate, and obtaining the complex phase multiferroic material. The ferroelectricsubstrate cannot recover to an original shape under the constraint of the ferromagnetic film, so that the stress is generated at an interface, and the magnetism of the ferromagnetic film is regulatedand controlled by the stress. With the existence of the pre-stress in the complex phase multiferroic material obtained by the present invention, a smaller external electric field can change the magnetization state of the ferromagnetic film, thereby reducing a response field.

A memory element (1) comprises a source electrode (12), a drain electrode (13) and a gate, wherein a memory state of the memory element is switchable by application of a voltage signal to the gate, and is readable by measuring a current-voltage characteristic between the source electrode and the drain electrode across a channel region (21). The gate comprises a multiferroic material (15). A magnetic field may be generated in the channel region (21). According to the invention, the multiferroic material (15) comprises a first and a second stable domain (15.1; 15.2), wherein a switching state of the first domain is set by application of a first write voltage signal between a gate electrode and the source electrode, and a switching state of the second domain is set by application of a second write voltage signal between the gate electrode and the drain electrode, whereby the memory element is a 2-bit memory element.

The invention provides a preparation method of multiferroic YFeO3 nano-fiber. The preparation method is characterized in that ferric nitrate, yttrium nitrate, polyvinylpyrrolidone and N,N-dimethyl formamide are uniformly mixed, a spinning solution is prepared, then an electrostatic spinning instrument is used for performing electrostatic spinning on the spinning solution, precursor fiber is obtained after the spinning solution is dried, then the precursor fiber is sintered, and the multiferroic YFeO3 nano-fiber is obtained. The YFeO3 nano-fiber prepared with the preparation method has a hexagonal crystal structure similar to that of YMnO3 and shows a new physical property, namely ferroelectricity, accordingly, the YFeO3 nano-fiber prepared with the method has ferroelectricity and ferromagnetism simultaneously, is a novel multiferroic material and can be applied to fields such as multi-state storage devices, double-read-write internal storage devices and the like.

The invention discloses a low-leakage-current semiconductor film heterojunction and a preparation method thereof. The low-leakage-current semiconductor film heterojunction is prepared by depositing a weak-ferroelectricity film layer with a perovskite structure on a substrate, and then depositing a multiferroic film on the ferroelectric film layer to form an ABO3 type multiferroic film/ABO3 ferroelectric film/substrate heterojunction film structure, wherein proper atmosphere and a proper annealing process are combined. The leakage current density of the film heterojunction is lower than that of a monolayer ABO3 type multiferroic film by about 3-5 orders of magnitudes.

The invention provides a completely-crystallized multiferroic film without producing impure phase and a preparation method of the completely-crystallized multiferroic film. The invention relates to a multiferroic film and a preparation method of the multiferroic film, solving the problems of conventional BiFeO3 (BFO) based film and conventional method that the film is relatively high in current leakage, low in ferromagnetic performance, and is reacted with a Pt bottom electrode to obtain Bi2Pt alloy, so that the comprehensive performance is reduced, and the completely-crystallized multiferroic film without producing impure phase cannot be prepared by the conventional method. The completely-crystallized multiferroic film without producing impure phase is prepared by barium strontium titanate based sol and BFO based sol. The preparation method comprises the steps as follows: 1, preparing a film for a buffering layer; and 2, depositing a BFO based film, and then carrying out quick annealing technology so as to obtain the completely-crystallized multiferroic film without producing impure phase. The preparation method provided by the invention is mainly used for preparing the completely-crystallized multiferroic film without producing impure phase.

The invention discloses an in-situ integration representation device of a multiferroic material nanoscale domain structure. The in-situ integration representation device comprises an atomic force microscopy in-situ incentive platform and an in-situ detection platform, the atomic force microscopy in-situ incentive platform is used for multiferroic structure in-situ incenting on detected multiferroic materials to enable an incenting point of the detected multiferroic materials to generate domain structure imaging signals, and the in-situ detection platform carries out in-situ real-time detection and data processing on the domain structure imaging signals and displays the in-situ imaging representation result of the multiferroic domain structure in real time. Through the device, in-situ, lossless, real-time, dynamic and integrated representation of a multiferroic material nanoscale ferroelectric domain and a ferromagnetic domain can be achieved.

Ferroelectric memory using multiferroics is described. The multiferrroic memory includes a substrate having a source region, a drain region and a channel region separating the source region and the drain region. An electrically insulating layer is adjacent to the source region, drain region and channel region. A data storage cell having a composite multiferroic layer is adjacent to the electrically insulating layer. The electrically insulating layer separated the data storage cell form the channel region. A control gate electrode is adjacent to the data storage cell. The data storage cell separates at least a portion of the control gate electrode from the electrically insulating layer.

The invention discloses a method for preparing room-temperature multiferroic BiFeO3-SrTiO3 sosoloid ceramics, belonging to the technical field of information functional materials. The BiFeO3-SrTiO3 ceramics prepared by using the method have the advantages of single-phase structure, low drain current, room-temperature ferroelectric/ferromagnetic coexistence, and the like.